Terms starting with "H"
HTTP/3 & QUIC
HTTP/3 runs over QUIC (UDP-based) instead of TCP — eliminating head-of-line blocking, reducing connection setup time, and improving performance on lossy networks.
6mo ago
Performance advanced
Hypermedia APIs — HATEOAS
REST APIs that include links in responses — clients discover available actions from the response rather than hardcoding URLs, making APIs self-describing and evolvable.
6mo ago
API Design advanced
Halstead Maintainability Index
2
A composite metric (0–100) combining lines of code, cyclomatic complexity, and Halstead volume to estimate maintainability.
6mo ago
Code Quality advanced
Hardcoded Credentials
3
Secrets, passwords, or API keys embedded directly in source code can be extracted from repositories or compiled binaries.
CWE-798 OWASP A2:2021
6mo ago
Security beginner
9.8
Hash Table
PHP 5.0+
3
A data structure that maps keys to values using a hash function, providing amortised O(1) average-case lookups, insertions, and deletions.
6mo ago
Data Structures intermediate
hash_equals()
PHP 5.6+
2
Constant-time string comparison that prevents timing attacks when validating tokens and CSRF values.
6mo ago
PHP intermediate
Header Injection
PHP 5.0+
User input included in an HTTP response header without stripping newlines enables response splitting and redirect hijacking.
CWE-113 OWASP A3:2021
6mo ago
Security intermediate
6.1
Health Check Endpoints
PHP 5.0+
3
Dedicated endpoints that report application and dependency status, enabling load balancers, container orchestrators, and monitors to route traffic correctly.
6mo ago
DevOps beginner
Heaps & Priority Queues
PHP 5.3+
2
A tree-based structure satisfying the heap property — min-heap: parent ≤ children; max-heap: parent ≥ children — enabling O(1) peek and O(log n) insert/extract for priority queues.
6mo ago
Data Structures intermediate
Heredoc / Nowdoc
PHP 5.0+
Heredoc (<<<EOT) and Nowdoc (<<<'EOT') provide multi-line string syntax; Nowdoc is the single-quoted equivalent with no variable interpolation.
6mo ago
PHP beginner
Hexagonal Architecture (Ports & Adapters)
PHP 5.0+
1
Isolates application core logic from external systems (HTTP, databases, queues) via ports (interfaces) and adapters (implementations).
6mo ago
Architecture advanced
HMAC (Hash-based Message Authentication Code)
PHP 5.1+
2
A keyed hash that verifies both the integrity and authenticity of a message — only someone with the secret key can produce or verify it.
OWASP A2:2021
6mo ago
Security intermediate
Host Header Injection
PHP 5.0+
1
A manipulated HTTP Host header is used by the application to generate URLs, enabling cache poisoning, password-reset hijacking, or SSRF.
CWE-116 OWASP A3:2021
6mo ago
Security intermediate
7.5
HTML Forms — Validation & Accessibility
HTML5
1
Native HTML form validation, input types, and accessibility patterns — using browser built-ins before reaching for JavaScript.
6mo ago
Frontend beginner
HTML Injection
PHP 5.0+
1
Unsanitised user input rendered as raw HTML allows attackers to inject arbitrary markup, defacing pages or phishing users.
CWE-80 OWASP A3:2021
6mo ago
Security beginner
6.1
htmlspecialchars()
PHP 5.0+
1
Converts HTML special characters to entities — the primary defence against XSS in HTML output contexts.
6mo ago
PHP beginner
HTTP Caching (ETags, Cache-Control)
1
Standard HTTP headers that instruct browsers and intermediary caches on how long to cache responses and when to revalidate.
6mo ago
Performance intermediate
HTTP Methods — Idempotency & Safety
2
Safe methods (GET, HEAD) have no side effects. Idempotent methods (GET, PUT, DELETE, HEAD, OPTIONS) produce the same result regardless of how many times they are called.
6mo ago
Networking intermediate
HTTP Parameter Pollution
PHP 5.0+
Submitting duplicate HTTP parameters exploits inconsistencies in how servers and applications parse repeated keys.
CWE-235 OWASP A3:2021
6mo ago
Security intermediate
6.5
HTTP Request Smuggling
Desynchronising front-end and back-end HTTP parsing via conflicting Content-Length and Transfer-Encoding headers to poison request queues.
CWE-444 OWASP A5:2021
6mo ago
Security advanced
9.8